Fix sendHeaders test for environment-based pings filter

Author: arcangelini

tests/phpunit/tests/wp/sendHeaders.php

@@ -8,6 +8,13 @@
 class Tests_WP_SendHeaders extends WP_UnitTestCase {
 	protected $headers_sent = array();
 
+	public function set_up() {
+		parent::set_up();
+
+		// Remove the environment-based filter to test core behavior in isolation.
+		remove_filter( 'pings_open', 'wp_disable_pings_open_for_environment' );
+	}
+
 	/**
 	 * @ticket 56068
 	 */